/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.mahout.cf.taste.impl.similarity.file;
import java.io.File;
import org.apache.mahout.cf.taste.impl.TasteTestCase;
import org.apache.mahout.cf.taste.impl.similarity.GenericItemSimilarity;
import org.apache.mahout.cf.taste.impl.similarity.GenericItemSimilarity.ItemItemSimilarity;
import org.apache.mahout.cf.taste.similarity.ItemSimilarity;
import org.junit.Before;
import org.junit.Test;
/** <p>Tests {@link FileItemSimilarity}.</p> */
public final class FileItemSimilarityTest extends TasteTestCase {
private static final String[] data = {
"1,5,0.125",
"1,7,0.5" };
private static final String[] changedData = {
"1,5,0.125",
"1,7,0.9",
"7,8,0.112" };
private File testFile;
@Override
@Before
public void setUp() throws Exception {
super.setUp();
testFile = getTestTempFile("test.txt");
writeLines(testFile, data);
}
@Test
public void testLoadFromFile() throws Exception {
ItemSimilarity similarity = new FileItemSimilarity(testFile);
assertEquals(0.125, similarity.itemSimilarity(1L, 5L), EPSILON);
assertEquals(0.125, similarity.itemSimilarity(5L, 1L), EPSILON);
assertEquals(0.5, similarity.itemSimilarity(1L, 7L), EPSILON);
assertEquals(0.5, similarity.itemSimilarity(7L, 1L), EPSILON);
assertTrue(Double.isNaN(similarity.itemSimilarity(7L, 8L)));
double[] valuesForOne = similarity.itemSimilarities(1L, new long[] { 5L, 7L });
assertNotNull(valuesForOne);
assertEquals(2, valuesForOne.length);
assertEquals(0.125, valuesForOne[0], EPSILON);
assertEquals(0.5, valuesForOne[1], EPSILON);
}
@Test
public void testNoRefreshAfterFileUpdate() throws Exception {
ItemSimilarity similarity = new FileItemSimilarity(testFile, 0L);
/* call a method to make sure the original file is loaded*/
similarity.itemSimilarity(1L, 5L);
/* change the underlying file,
* we have to wait at least a second to see the change in the file's lastModified timestamp */
Thread.sleep(2000L);
writeLines(testFile, changedData);
/* we shouldn't see any changes in the data as we have not yet refreshed */
assertEquals(0.5, similarity.itemSimilarity(1L, 7L), EPSILON);
assertEquals(0.5, similarity.itemSimilarity(7L, 1L), EPSILON);
assertTrue(Double.isNaN(similarity.itemSimilarity(7L, 8L)));
}
@Test
public void testRefreshAfterFileUpdate() throws Exception {
ItemSimilarity similarity = new FileItemSimilarity(testFile, 0L);
/* call a method to make sure the original file is loaded */
similarity.itemSimilarity(1L, 5L);
/* change the underlying file,
* we have to wait at least a second to see the change in the file's lastModified timestamp */
Thread.sleep(2000L);
writeLines(testFile, changedData);
similarity.refresh(null);
/* we should now see the changes in the data */
assertEquals(0.9, similarity.itemSimilarity(1L, 7L), EPSILON);
assertEquals(0.9, similarity.itemSimilarity(7L, 1L), EPSILON);
assertEquals(0.125, similarity.itemSimilarity(1L, 5L), EPSILON);
assertEquals(0.125, similarity.itemSimilarity(5L, 1L), EPSILON);
assertFalse(Double.isNaN(similarity.itemSimilarity(7L, 8L)));
assertEquals(0.112, similarity.itemSimilarity(7L, 8L), EPSILON);
assertEquals(0.112, similarity.itemSimilarity(8L, 7L), EPSILON);
}
@Test(expected = IllegalArgumentException.class)
public void testFileNotFoundExceptionForNonExistingFile() throws Exception {
new FileItemSimilarity(new File("xKsdfksdfsdf"));
}
@Test
public void testFileItemItemSimilarityIterable() throws Exception {
Iterable<ItemItemSimilarity> similarityIterable = new FileItemItemSimilarityIterable(testFile);
GenericItemSimilarity similarity = new GenericItemSimilarity(similarityIterable);
assertEquals(0.125, similarity.itemSimilarity(1L, 5L), EPSILON);
assertEquals(0.125, similarity.itemSimilarity(5L, 1L), EPSILON);
assertEquals(0.5, similarity.itemSimilarity(1L, 7L), EPSILON);
assertEquals(0.5, similarity.itemSimilarity(7L, 1L), EPSILON);
assertTrue(Double.isNaN(similarity.itemSimilarity(7L, 8L)));
double[] valuesForOne = similarity.itemSimilarities(1L, new long[] { 5L, 7L });
assertNotNull(valuesForOne);
assertEquals(2, valuesForOne.length);
assertEquals(0.125, valuesForOne[0], EPSILON);
assertEquals(0.5, valuesForOne[1], EPSILON);
}
@Test
public void testToString() throws Exception {
ItemSimilarity similarity = new FileItemSimilarity(testFile);
assertTrue(!similarity.toString().isEmpty());
}
}